Tetracycline is a broad-spectrum antibiotic that has been used extensively for treatment of urogenital tract diseases. Over the last few years we have shown that high level tetracycline resistance (Tcr) in Neisseria gonorrhoeae, Gardnerella vaginalis, Mycoplasma hominis, Ureaplasma urealyticum as well as a number of anaerobic species is strongly associated with the presence of the Tet M determinant. These Tc/r strains have become widespread and in some cases resulted in changes in therapy recommendations for treatment of urogenital tract disease. We will examine the 25.2 Mdal gonococcal and the 34 Mdal Haemophilus ducreyi Tet M containing plasmids. Specifically we will examine the flanking regions around the Tet M determinant in the plasmids, determine how much of the transposon sequences are present, determine the host range, and continue to molecularly characterize these two plasmids. We will continue to examine the transfer of the Tet M determinant among natural clinical isolates to determine if a variety of recipients, representing different species, can be used as donors, if the transconjugants can also act as donors of the Tet M determinant, determine if all members of a species has donor ability, and how many of the different species can act as donors. We will examine the flanking regions around the Tet M determinants found in the chromosome of various species, determine the sequences in different strains of the same species, and compare them with other species. We will compare the distribution of the Tet M determinant to the 12 other well characterized tet determinants in a group of strains, representing a variety of species, isolated from the urogenital tract and determine if any of them are transferable to other strains.